Endoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. Consequently, significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar. These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.).
Positioning the end effector is constrained by the trocar. Generally these endoscopic surgical instruments include a long shaft between the end effector and a handle portion manipulated by the clinician, this long shaft enables insertion to a desired depth and rotation about the longitudinal axis of the shaft, thereby positioning the end effector to a degree. With judicious placement of the trocar and use of graspers, for instance, through another trocar, often this amount of positioning is sufficient. Surgical stapling and severing instruments, such as described in U.S. Pat. No. 5,465,895, are an example of an endoscopic surgical instrument that successfully positions an end effector by insertion and rotation.
More recently, U.S. Appl. Ser. No. 10/443,617, “SURGICAL STAPLING INSTRUMENT INCORPORATING AN E-BEAM FIRING MECHANISM” to Shelton et al., filed on 20 May 2003, describes an improved “E-beam” firing bar for severing tissue and actuating staples. Some of the additional advantages include affirmatively space the jaws of the end effector, even if slightly too much or two little tissue is clamped for optimal staple formation. Moreover, the E-beam firing bar includes engages the end effector and staple cartridge in a way that enables several beneficial lockouts to be incorporated.
Depending upon the nature of the operation, it may be desirable to further adjust the positioning of the end effector of an endoscopic surgical instrument rather than being limited to insertion and rotation. In particular, it is often desirable to orient the end effector at an axis transverse to the longitudinal axis of the shaft of the instrument. The transverse movement of the end effector relative to the instrument shaft is conventionally referred to as “articulation”. This articulated positioning permits the clinician to more easily engage tissue in some instances. In addition, articulated positioning advantageously allows an endoscope to be positioned behind the end effector without being blocked by the instrument shaft.
While the aforementioned non-articulating stapling and severing instruments have great utility and may be successfully employed in many surgical procedures, it is desirable to enhance their operation with the ability to articulate the end effector, thereby giving greater clinical flexibility in their use.
Approaches to articulating a stapling and severing tend to be complicated by integrating control of the articulation along with the control of closing the end effector to clamp tissue and firing (i.e., stapling and severing) the end effector within the small diameter constraints of an endoscopic instrument. Generally, the three control motions are all transferred through the shaft as longitudinal translations. For instance, U.S. Pat. No. 5,673,840 discloses an accordion-like articulation mechanism (“flex-neck”) that is articulated by selectively drawing back one of two connecting rods through the implement shaft, each rod offset respectively on opposite sides of the shaft centerline.
Another example of longitudinal control of an articulation mechanism is U.S. Pat. No. 5,865,361 that includes an articulation link offset from a camming pivot such that pushing or pulling longitudinal translation of the articulation link effects articulation to a respective side. Similarly, U.S. Pat. No. 5,797,537 discloses a similar rod passing through the shaft to effect articulation.
While these longitudinally controlled articulation mechanisms have provided certain advantages to surgical instruments such as for endoscopic stapling and severing, it is believed that an alternative articulation motion would provide additional design flexibility. In particular, advantageous approaches are described in the four above cross-referenced and co-pending applications wherein a rotational motion relative to a longitudinal axis of the shaft transfers an articulating motion to an articulation mechanism coupling the end effector to the shaft.
What would be further desirable is to retain the advantages of an E-beam firing bar in a surgical stapling and severing instrument in combination with a rotationally controlled articulation mechanism. Consequently, a significant need exists for such an instrument incorporating a firing beam that advantages severs clamped tissue, engages the jaws of the end effector for affirmatively-controlled stapling, yet is coupled for firing motion through an articulation mechanism.